Dynamics of Silent Universes

We investigate the local non--linear dynamics of irrotational dust with vanishing magnetic part of the Weyl tensor, $H_{ab}$. Once coded in the initial conditions, this dynamical restriction is respected by the relativistic evolution equations. Thus, the outcome of the latter are {\it exact solutions} for special initial conditions with $H_{ab}=0$, but with no symmetries: they describe inhomogeneous triaxial dynamics generalizing that of a fluid element in a Tolman--Bondi, Kantowski--Sachs or Szekeres geometry. A subset of these solutions may be seen as (special) perturbations of Friedmann models, in the sense that there are trajectories in phase--space that pass arbitrarily close to the isotropic ones. We find that the final fate of ever--expanding configurations is a spherical void, locally corresponding to a Milne universe. For collapsing configurations we find a whole family of triaxial attractors, with vanishing local density parameter $\Omega$. These attractors locally correspond to Kasner vacuum solutions: there is a single physical configuration collapsing to a degenerate {\it pancake}, while the generic configuration collapses to a triaxial {\it spindle} singularity. These {\it silent universe} models may provide a fair representation of the universe on super horizon scales. Moreover, one might conjecture that the non--local information carried by $H_{ab}$ becomes negligible during the late highly non--linear stages of collapse, so that the attractors we find may give all of the relevant expansion or collapse configurations of irrotational dust.Comment: 40 pages with 4 figures, compressed and uuencoded PostScript file, submitted to ApJ, SISSA preprint Ref. 85/94/

Innovative Rotman lens setup for extended scan range array antennas

The aim of this work is to design a smart and cost effective 24 GHz Short Range Radar (SRR) array antenna system for automotive applications. The beam forming network consists of a hybrid solution including an analog phase shifter, realized with a Rotman lens, and an additional digital phase shifting stage on array side allowing to select between two states, and consequently to enhance the scan angle. This paper will demonstrate that this new concept allows to double the scanning capability of the array with respect to a design employing only the Rotman lens

Compact Extended Scan Range Antenna Array based on Rotman Lens

This article proposes an innovative method for extending the scan range of phased arrays based on Rotman lens by a factor two. The main objective is to take advantage of the performance of the Rotman lens as beamforming network, resolving its intrinsic increase of phase error and coupling losses when wide scan angles are required. The proposed concept aims to overcome these limitations by introducing the combination of two specific operations called “complete beam shifting (CBS)” and “beam mirroring (BM).” The described technique is applied to a 24 GHz scanning array antenna system, designed and manufactured by taking into consideration fabrication and related cost issues. Finally, the proposed concept has been validated through measurements

Adapting Quality Assurance to Adaptive Systems: The Scenario Coevolution Paradigm

From formal and practical analysis, we identify new challenges that self-adaptive systems pose to the process of quality assurance. When tackling these, the effort spent on various tasks in the process of software engineering is naturally re-distributed. We claim that all steps related to testing need to become self-adaptive to match the capabilities of the self-adaptive system-under-test. Otherwise, the adaptive system's behavior might elude traditional variants of quality assurance. We thus propose the paradigm of scenario coevolution, which describes a pool of test cases and other constraints on system behavior that evolves in parallel to the (in part autonomous) development of behavior in the system-under-test. Scenario coevolution offers a simple structure for the organization of adaptive testing that allows for both human-controlled and autonomous intervention, supporting software engineering for adaptive systems on a procedural as well as technical level.Comment: 17 pages, published at ISOLA 201

The ARC-EN-CIEL radiation sources

MOPC005International audienceThe ARC-EN-CIEL (Accelerator-Radiation for Enhanced Coherent Intense Extended Light) project proposes a panoply of light sources for the scientific community on a 1 GeV superconducting LINAC (phase 2) on which two ERL loops (1 and 2 GeV) are added in phase 3. LEL1 (200-1.5 nm), LEL2 (10-0.5 nm) and LEL4 (2-0.2 nm) are three kHz High Gain Harmonic Generation Free Electron Laser sources seeded with the High order Harmonics generated in Gas, with 100-30 FWHM pulses. A collaboration, which has been set-up with the SCSS Prototype Accelerator in Japan to test this key concept of ARC-EN-CIEL, has led to the experimental demonstration of the seeding with HHG and the observation up the 7th non linear harmonic with a seed at 160 nm. LEL3 (40-8 nm) installed on the 1 GeV loop is a MHz FEL oscillator providing higher average power and brilliance. In addition, in vacuum undulator spontaneous emission source extend the spectral range above 10 keV and intense THz radiation is generated by edge radiation of bending magnets. Optimisations and light sources characteristics are described

AB0413 HIGH-RESOLUTION COMPUTED TOMOGRAPHY FOR THE SCREENING, RE-SCREENING AND FOLLOW-UP OF SYSTEMIC SCLEROSIS RELATED INTERSTITIAL LUNG DISEASE: RESULTS OF A EUSTAR-SCTC SURVEY

Background:High-resolution computed tomography (HRCT) is the gold standard diagnostic test for Interstitial lung disease (ILD), a significant cause of morbidity and mortality in systemic sclerosis (SSc). Different algorithms have been proposed for the screening of SSc-ILD, including the use of pulmonary function tests (Forced Vital Capacity - FVC, Lung Diffusion of Carbone Monoxyde - DLCO). A prior survey reported that 50-66% of general rheumatologists and SSc experts ordered HRCT for ILD screening in newly diagnosed SSc patients (1).Objectives:Given the recent availability of on-label treatment for SSc-ILD (2), the publication of consensus recommendations for the identification of SSc-ILD (3) and recent awareness programs for the use of HRCT to detect SSc-ILD, we aimed to re-evaluate the use of HRCT for screening, re-screening and follow-up of SSc-ILD.Methods:An invitation was sent to the European Scleroderma Trials and Research (EUSTAR) and Scleroderma Clinical Trials Consortium (SCTC) members, also advertised through social media. Answers were recorded between Nov 25th and Dec 31st 2020. Questions were asked on the use of chest HRCT at baseline, the re-screening of patients with a negative baseline HRCT and the follow-up of HRCT positive SSc-ILD patients. When HRCT was not routinely requested, additional details were collected about the parameters guiding its use. The results of the survey were tested for association with geographical origin, medical specialty, working environment, SSc referral institute and scientific group membership of the responders, using Chi-squared test.Results:205/630 (32.5%) physicians replied to the survey. Participants were widely distributed in terms of geographical origin (130 Europe, 23 Asia, 23 North America, 31 other continents), medical specialty (156 rheumatology, 21 internal medicine, 14 clinical immunology, 14 other), working environment (176 University Hospital, 12 community hospital, 17 other), SSc dedicated clinic (179 referral and 26 non-referral) and scientific group membership (98 EUSTAR, 42 SCTC, 42 EUSTAR and SCTC, 23 not declared).At SSc diagnosis, 95.7% of responders would perform HRCT: 66.7% as routine screening for ILD (67,4% of SSc referral and 62% for non-referral physicians) and 29% for diagnostic purposes (among the latter, if crackles on auscultation – 92.5%, FVC<80% predicted - 86.6%, FVC±DLCO relative decline reaching the current definition of ILD progression, 86.6% or dyspnea at rest/exercise - 85.1/83.3%).During follow-up, 78.8% of responders would repeat an HRCT in baseline negative cases: 20.3% as a yearly routine screening and 64.5% for diagnostic aims (decision on the latter group was more frequently driven by FVC±DLCO relative decline indicative of ILD progression– 90.6%, new onset or worsening of dyspnoea at rest/exercise – 80.5/86.6%, new onset or worsening of lung crackles on auscultation – 82.6%).Finally, 94.5% of responders would repeat a chest HRCT after SSc-ILD diagnosis: 36.8% as a yearly routine and 56.7% according to clinical evaluation (driven by new FVC±DLCO relative decline based ILD progression – 90.8%, new onset or worsening of dyspnoea at rest/exercise – 83.2/81.7%; 5.2% to evaluate treatment effects). We found no difference in the distribution of answers among groups.Conclusion:The use of baseline HRCT for the screening of SSc-ILD has slightly increased in non-referral and remained stable in referral centers compared to previous surveys, indicating that the implementation of guidelines might be successful and awareness programs should be continued. In addition, we provide new data on use of HRCT in re-screening and follow-up. The development of validated algorithms to further support the appropriate application of HRCT at follow-up is highly needed.References:[1]Bernstein EJ et al. Arthritis Rheumatol. 2018 Jun;70(6):971-972.[2]Distler O et al. N Engl J Med. 2019 Jun 27;380(26):2518-2528.[3]Hoffmann-Vold AM et al. The Lancet Rheumatology, Volume 2, Issue 2, e71 - e83.Disclosure of Interests:Cosimo Bruni Speakers bureau: Actelion, Consultant of: Eli Lilly, Grant/research support from: Foundation for Research in Rheumatology (FOREUM), Gruppo Italiano Lotta alla Sclerodermia (GILS), Fondazione Italiana per la Ricerca sull'Artrite (FIRA), New Horizon Fellowship, European Sclerodermia Trial and Reserach (EUSTAR) Group., Lorinda Chung Consultant of: Boehringer Ingelheim, Eicos, Mitsubishi Tanabe, Reata., Anna-Maria Hoffmann-Vold Consultant of: Actelion, ARXX therapeutics, Bayer, Boehringer-Ingelheim, Medscape, MSD, Lilly, Roche, Shervin Assassi Speakers bureau: Integrity Continuing Education, Consultant of: Boehringer Ingelheim, Novartis, and Corbus, Armando Gabrielli: None declared, Dinesh Khanna Consultant of: Acceleron, Actelion, Abbvie, Amgen, Bayer, Boehringer Ingelheim, CSL Behring, Corbus, Gilead, Galapagos, Genentech/Roche, GSK, Horizon, Merck, Mitsubishi Tanabe Pharma, Sanofi-Aventis, and United Therapeutics Leadership, Grant/research support from: NIH, Immune Tolerance Network, Bayer, BMS, Horizon, Pfizer, Employee of: Equity position – Chief Medical Officer, Eicos Sciences, Inc., Elana Bernstein Consultant of: Boehringer Ingelheim, Oliver Distler Consultant of: Abbvie, Acceleron Pharma, Amgen, AnaMar, Arxx Therapeutics, Baecon Discovery, Blade Therapeutics, Bayer, Boehringer Ingelheim, ChemomAb, Corbus Pharmaceuticals, CSL Behring, Galapagos NV, Glenmark Pharmaceuticals, GSK, Horizon (Curzion) Pharmaceuticals, Inventiva, iQvia, Italfarmaco, iQone, Kymera Therapeutics, Lilly, Medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Novartis, Pfizer, Roche, Sanofi, Serodapharm, Topadur, Target Bioscience and UCB., Grant/research support from: Abbvie, Acceleron Pharma, Amgen, AnaMar, Arxx Therapeutics, Baecon Discovery, Blade Therapeutics, Bayer, Boehringer Ingelheim, ChemomAb, Corbus Pharmaceuticals, CSL Behring, Galapagos NV, Glenmark Pharmaceuticals, GSK, Horizon (Curzion) Pharmaceuticals, Inventiva, iQvia, Italfarmaco, iQone, Kymera Therapeutics, Lilly, Medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Novartis, Pfizer, Roche, Sanofi, Serodapharm, Topadur, Target Bioscience and UCB. Patent issued "mir-29 for the treatment of systemic sclerosis" (US8247389, EP2331143)

Regular second order perturbations of binary black holes: The extreme mass ratio regime

In order to derive the precise gravitational waveforms for extreme mass ratio inspirals (EMRI), we develop a formulation for the second order metric perturbations produced by a point particle moving in the Schwarzschild spacetime. The second order waveforms satisfy a wave equation with an effective source build up from products of the first order perturbations and its derivatives. We have explicitly regularized this source at the horizon and at spatial infinity. We show that the effective source does not contain squares of the Dirac's delta and that perturbations are regular at the particle location. We introduce an asymptotically flat gauge for the radiation fields and the $\ell=0$ mode to compute explicitly the (leading) second order $\ell=2$ waveforms in the headon collision case. This case represents the first completion of the radiation reaction program self-consistently.Comment: 28 pages, no figur

Uniqueness of the gauge invariant action for cosmological perturbations

In second order perturbation theory different definitions are known of gauge invariant perturbations in single field inflationary models. Consequently the corresponding gauge invariant cubic actions do not have the same form. Here we show that the cubic action for one choice of gauge invariant variables is unique in the following sense: the action for any other, non-linearly related variable can be brought to the same bulk action, plus additional boundary terms. These boundary terms correspond to the choice of hypersurface and generate extra, disconnected contributions to the bispectrum. We also discuss uniqueness of the action with respect to conformal frames. When expressed in terms of the gauge invariant curvature perturbation on uniform field hypersurfaces the action for cosmological perturbations has a unique form, independent of the original Einstein or Jordan frame. Crucial is that the gauge invariant comoving curvature perturbation is frame independent, which makes it extremely helpful in showing the quantum equivalence of the two frames, and therefore in calculating quantum effects in nonminimally coupled theories such as Higss inflation.Comment: 27 page

ERL Scheme for Compton Polarised Positron Sources

International audienceOne of the main challenges for the future linear colliders projects (ILC and CLIC) is to design an efficient positron source taking into account the constraints imposed by the target heating. At present, different schemes have been analysed to produce high energy gammas and to convert them in an amorphous target. One of them considers the possibility to boost the energy of the backscattered photons of a laser pulse by Compton effect. This method is very attractive since the source is independent from the main Linac and since the photon helicity is conserved in Compton scattering and subsequently transferred to the produced pairs. This allows the physics experiments disposing of both positron and electron polarised sources. Different schemes have been proposed to provide the electron beam for the Compton collisions. taking into account the constraint imposed by the low value of the Thomson cross section. One of the explored possibilities is to design an ERL with relatively low repetition frequency, high charge per pulse and then to stack the produced positrons in an accumulation ring. Different considerations on this scheme will be illustrated and the main constraints discussed. MO6RFP06

The Hubble rate in averaged cosmology

The calculation of the averaged Hubble expansion rate in an averaged perturbed Friedmann-Lemaitre-Robertson-Walker cosmology leads to small corrections to the background value of the expansion rate, which could be important for measuring the Hubble constant from local observations. It also predicts an intrinsic variance associated with the finite scale of any measurement of H_0, the Hubble rate today. Both the mean Hubble rate and its variance depend on both the definition of the Hubble rate and the spatial surface on which the average is performed. We quantitatively study different definitions of the averaged Hubble rate encountered in the literature by consistently calculating the backreaction effect at second order in perturbation theory, and compare the results. We employ for the first time a recently developed gauge-invariant definition of an averaged scalar. We also discuss the variance of the Hubble rate for the different definitions.Comment: 12 pages, 25 figures, references added, clarity improved, frame switching subtlety fixed, results unchanged, v3 minor typos fixe